Captain Matt Worman, 30, was commissioned four years ago as an education officer in the army. After learning some Pashtu on an introductory course, he then opted to do another 15 months intensive training in the language. Following a deployment as a military linguist in Afghanistan, he is back in the UK and soon to take up a position as second-in-command of the foreign languages wing at the Defence Centre for Languages and Culture.

I'd studied French and German at school, and taught English in China for five months before going to university. That time gave me a profound insight into another culture. Even though I didn't develop much of a grasp of Chinese, I came back home with a real appetite to learn more about how people lived in very different parts of the world.

At university I did law and then worked in a number of jobs from youth offending to Sainsbury's, but going to Sandhurst gave me some really interesting options. My younger brother was in the army already and had studied Pashtu and loved it, so I leaped at the chance to learn when it came along.

On that first 10-week course, we were taught by Afghan nationals. It was classroom based, but there were practical elements including military exercises which put you in scenarios where you had to act as an interpreter, for instance. By the end of the course you get to level 1 in ability, so slightly below a GCSE, but not much. You have to be rigid with the effort and time you put in. With Pashtu, it's about reprogramming your brain. Having a sentence with a whole load of content and meaning and then sticking the verb at the end is completely alien to native English speakers.

Enrolling on the longer course was great because I'd really enjoyed getting to grips with Pashtu at an elementary level. But when I was sent out as a military linguist on a patrol base in Afghanistan, I definitely felt apprehensive. Within an hour and a half of arriving I found myself in a room with eight Afghan security personnel who spoke very little English and sounded nothing like my tutors. It was daunting, but over the months I spent with them they became such close friends.

Speaking the language allows you an insight into people's minds and souls, and that depth of friendship is something you'd never get by communicating through a third party. In this sort of setting, you talk about everything; you might be discussing a really tragic incident, and then next minute you'd be talking about the London Eye.

Those relationships became enduring friendships because they're built on a mutual interest in each others' cultures. I remember a time when one of my Afghan colleagues lost a close relative in terrible circumstances. Just being able to offer a few words of condolence in his own language made a difference. He told me later that it had meant a lot.

The trust and respect and loyalty our little team had developed by the end of my tour was built through learning about the way they lived and their customs. You come to understand, through the language, their way of thinking. In places like Afghanistan, knowing the language makes you safer, too. Understanding the nuances of what's going on, the little indications in conversations that you'd otherwise have no idea of, means you can avoid overstepping a line.

In some of the Afghan towns I was going into, funnily enough, they weren't so surprised to hear I was speaking Pashtu, because people on patrol had got to the level of being able to say the basics. But speaking a language is one thing, and knowing a bit about the people you're likely to meet and the difficulties they're facing is another.

You need to have an interest. You need to listen. If you go into a village and the harvest has failed and people are hungry and getting desperate ... that's when it's about relating as one human being to another, and both language and attitude matter. You hear different things. You understand their experience differently.

Defence really gets this now. The lesson we've learnt from Afghanistan and Iraq, but also from Sierra Leone and Bosnia, is about the importance of language and culture. Our new defence centre for languages and culture is uniting all languages taught in the military under one centralised command in order to share best practice. We've also learned that language acquisition can't be reactive; it has to be proactive, because of the sheer time it takes to learn to any useful level.

We teach 40 languages, and on an average day last year, 220 students were studying on a long language course. About a quarter of those are our intelligence specialists. A third to a half were learning current operational languages, so Pashtu and Dari, and also Farsi. The rest were studying Arabic, Spanish, Russian and French – there are 900 million of the world's population who speak those, so we have to keep our hand in. When you're fluent, you become a very prized commodity in the military, and we want to retain and invest in the soldiers and officers who have these skills.

Now I'm back in the UK, I manage the design and delivery for our Pashtu courses. I've got Russians next door, Spaniards the other side of me, I work with Afghans every single day – it's a hugely dynamic environment to be in. The world opens up to you. As to the future, I would certainly like to travel. Long-term, I'm thinking of work with the Foreign and Commonwealth Office, or maybe trying to get a job with a foreign aid organisation. Once you've had experience of languages and the cultural study of places, it's hard to turn your back on.